CVE-2026-42375

HighCVSS 8.8/10Last modified Oct 26, 2026

Description

D-Link DIR-600L Hardware Revision A1 (End-of-Life) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /bin/telnetd.sh with the username "Alphanetworks" and the static password "wrgn35_dlwbr_dir600l" read from /etc/alpha_config/image_sign. The custom telnetd binary accepts a -u user:password flag, and the custom login binary uses strcmp() to validate credentials. Successful authentication grants an unauthenticated attacker on the local network a root shell with full administrative control. The device has reached End-of-Life (EOL) and will not receive patches.

Metrics

CVSS 3.1 8.8/10CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness enumeration

CWE-798

Affected software

Vendor	Product	Versions
D-Link	DIR-600L Firmware	A1

References

https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-Exploit, Third Party Advisory
https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-Exploit, Third Party Advisory

Timeline

Published: May 4, 2026
Last modified: Oct 26, 2026
NVD status: Analyzed

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